What Is A Generator Transfer Switch? How Does It Work?

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Most commonly, portable generators power lights and TVs, microwaves, and other plug-in appliances – appliances that can be connected to them with an extension cord (often referred to as generator cord). 

Unfortunately, some critical appliances you may need in an emergency can’t be plugged in. There is no plug coming from a furnace for instance. 

To operate items like a well-pump, furnace, or central air conditioner, which are wired directly into your home’s electricity, you will need a generator transfer switch.

So, what is a generator transfer switch? How does it work?

Keep on reading.

What Is A Generator Transfer Switch?

transfer switch

The generator transfer switch is actually one of the most important parts of a backup generator system. Sometimes, it is also referred to as a transfer switch, manual transfer switch, and power transfer switch.

The transfer switch simply allows the generator power to interface with your home and providing backup electricity. 

It eliminates the need to run multiple extension cords for many appliances and allows your generator to safely power entire rooms or circuits in a building or home.

The transfer switch has to be installed by a licensed electrician. The installation will cost about $400 to $600 in labor depending on the type of the generator and your location.

Why Is Transfer Switch Important?

Manual transfer switches make controlling your generator load particularly simple. They perform another important function. Transfer switches prevent the potentially lethal condition known as a back feed. 

Back feed occurs when the electricity produced by a portable or home generator enters outside lines, putting unsuspecting utility-company workers at risk for electrocution as they attempt to resurrect power. 

To avert this danger, a portable or home generator must never be plugged directly into a home’s wall outlet. 

It is worth noting that, because utility workers doing their jobs are left so vulnerable (to the threat of back feed), many jurisdictions have criminalized the reckless or improper use of a portable generator. 

Steep fines and even incarceration can result in a conviction (See California Health and Safety Code).

How Transfer Switches Work

fuse box

A generator transfer switch is installed beside your fuse box, and then hardwired to the circuits you’ll wish to run in an emergency.

Most manual transfer switches can run from 4 to 6 circuits. How many of these circuits can be run simultaneously will depend on the wattage of your generator. 

There are large manual transfer switches that can channel power to an entire building or house. As a rule, these models will have a 10 or 12-circuit capacity. 

They will also require a portable or home generator of over 10,000 watts to operate them effectively.

To gets a feel for the circuits that can be hooked to a manual transfer switch, examine your fuse box. Any of the circuits you see, which can be turned on and off by the switches in your fuse box, can also be run with a portable generator. 

Your kitchen will probably have its own circuit. Probably so will your living room, and each bathroom in the house. 

Many homeowners choose to power a utility or laundry room, frequently the location of a water heater or furnace. After you have chosen the circuits you want hardwired, it’s a quick and simple procedure for a licensed electrician to connect these to the circuits of the transfer switch. 

You can put away the multiple generator cords, so tedious and easy to tangle, that once hooked appliances into your generator’s outlet panel. 

Now you’ll need one power cord to plug the generator into the manual transfer switch for information on selecting the right power cord to accompany your generator and transfer switch.

Also read: Why do you need a power surge protector for your home?

Generator Transfer Switches Make Controlling Loads Easy

Most portable or home generators aren’t large enough to power all circuits hardwired to the transfer switch simultaneously. 

By employing flip-up switches on the face of the manual transfer switch, you can choose to run one circuit at a time – or two or more circuits together, depending on your needs, and generator capacity. 

With the activation of one circuit, for instance, power can be directed to your kitchen, where it runs a refrigerator and microwave. Then, by turning off that switch and activating another, redirected to the laundry to operate a water heater, furnace, or perhaps a central air conditioner. 

Activating the third circuit can send generator electricity to lights and a TV in the living room, or to a space heater and electric blanket inside a bedroom.

Also related: You can also connect a generator without a transfer switch.

What Is The Best Transfer Switch For Your Generator?

There are many good transfer switches for generators in the market. They vary in terms of Wattage, Ampere, type of switches, and etc.

From my research, these are the best transfer switches you might want to consider (all link to Amazon, prices updated daily):

Reliance Controls 31410CRK Pro/Tran 10-Circuit 30 Amp Generator Transfer Switch Kit,Gray
  • Convenient transfer switch kit, ideal for your circuitry and multi-wiring needs, is also made for reliably-fast installation in both residential and commercial applications
  • Designed specifically for generators up to 7,500 maximum running watts
  • 18-inch flexible conduit whip attaches easily to the load center
  • Maximum single-pole circuits: 10 / Maximum double-pole circuits: 5
  • Features a rugged, powder-coated steel cabinet. six combination knockouts and more
Connecticut Electric EGS107501G2KIT EmerGen EGS107501G2 Manual Transfer Switch Kit 30 Amp, 10-Circuit, 7500 Watts, For Portable Generator
  • FOR PORTABLE GENERATOR: This transfer kit is designed for use with emergency generators that have up to a 30 amp output, Nema L1430. With easy-to-follow instructions, this unit is incredibly easy to install and is a cheaper alternative to running your portable generator without it.
  • VOLTAGE: This transfer switch kit is designed with the capability of 2 pole circuits and allows 240-volt circuits, making it perfect for well or water sump pump applications. If one of the installed 2-pole circuits are not needed, the tie bar can be removed to allow for 2 single pole circuits.
  • INDOOR OR OUTDOOR: The designed enclosures of the power inlet and transfer switches to be used either indoors or outdoors and have a NEMA 3R rainproof rating allowing the kit to be installed wherever is convenient for you and you home.
  • COMPATIBLE WITH ALL LOAD CENTERS: This backup generator inverter is compatible with all residential load centers including: Challenger, Cutler Hammer, GE, Home line, Siemens, Square D, and Westinghouse load centers.
  • POWER SURGE PROTECTION: The double throw rocker switches absolutely eliminate the possibility of power back feeding to the utility line or to your generator when power is restored. All Connecticut Electric products are ETL listed, ensuring its compliance to UL Standard.
Generac 6852 Home Link Upgradeable Transfer Switch Kit, 30 Amp
  • Versatile: Can be upgraded later for use with a Generac Home Standby Generator (max 11 kW)
  • Power indicator lights: Displays when you have utility power or generator power
  • Safe: Prevents dangerous back-feeding to avoid injuring utility line workers
  • Powers hard-wired circuits: Directly powers hard-wired appliances such as your furnace, well pump, and lights
  • Easy to maintain and expand: Interchangeable type circuit breakers make it easy to reconfigure, replace, or expand the circuits in your switch

Last update on 2022-06-22 at 01:36 / Affiliate links / Images from Amazon Product Advertising API


I recommend that you always solicit a qualified licensed electrician to install a manual transfer switch. A licensed electrician will be familiar with building codes in your area. 

Some municipalities require that a permit be obtained before transfer equipment is installed. An electrician will know when a permit is needed, and how to go about acquiring one. 

Remember that transfer equipment improperly installed can void a homeowner’s insurance policy in the event of property damage or serious injury. 

Given the possible downside, the extra expense of a qualified electrician is money well spent.